Whether the goal is to perform medical imaging for dermatology or wound care purposes, or to collect data for biometric applications, there is a critical need to collect the images of the human body in a precise, repeatable, and high-quality manner.
Chromasens Corona II LED Module. Image Credit: Chromasens GmbH
Scientists at the Brno University of Technology1 (Brno, Czech Republic) have created a prototype of an optical scanning system based on linescan imaging instead of a traditional 2D sensor. Leveraging the Chromosens Corona II LED Illumination module as the light source, the experimental system can change the field of view based on the diagnostic needs and thus allow the scanning of body parts of various sizes without having to change the physical configuration, whether the part is a finger, hand or entire arm. Another advantage is that it doesn't require the patient to touch the scanning surface. Hygienic demands dictate that the devices used by multiple people need to be cleaned and disinfected at regular intervals, especially in the post-COVID era.
Chromsens Corona II LED lighting modules output brightness of up to 3,500,000 lux with excellent homogeneity via a patented reflector design that shapes light, therefore eliminating chromatic aberrations. The Brno University research team selected a 190mm top light dark field module for their device with a minimum white illuminance of 800,000 lux.
Besides a linescan camera equipped with a 50 mm f/1.8D lens and the Chromasens LED lighting, the optical scanning device employs a linear movement system, a Chromasens XLC4-1 LED control unit, a Raspberry Pi 3 single-board computer, and a microcontroller unit. It is capable of producing 350 dpi images of the variable field of view without having to make concessions to the quality due to its mechanical properties. It allows for objects up to 120 × 43 cm (47.2 inches x 16.9 inches) in size to be scanned while maintaining the 350 dpi spatial resolution.
The Chromasens XLC4-1 unit is controlled over a Telnet interface. A series of simple commands provided by the unit's documentation sets the intensity of Corona II lighting and turns the light module on and off. Commands to monitor the status of the illumination unit and the module were also utilized. The linescan camera acquired 5,120 lines at a rate of 500 lines per second. It used the GigE interface and an API script was developed to handle its initialization, data grabbing, and image construction. Triggering and frame grabbing are performed using software scripts.
The device is mainly intended to be used for monitoring hand diseases and disorders, such as eczema, as well as various skin growths, such as nevus, to monitor their size and area. Images collected by the scanner are also of sufficient quality to perform recognition based on hand geometry if other biometrics are unavailable, for example, due to injuries such as a burn or skin diseases.